/*
 *  The MIT License
 *
 *  Copyright 2010 Sony Ericsson Mobile Communications. All rights reserved.
 *  Copyright 2014 Sony Mobile Communications AB. All rights reserved.
 *
 *  Permission is hereby granted, free of charge, to any person obtaining a copy
 *  of this software and associated documentation files (the "Software"), to deal
 *  in the Software without restriction, including without limitation the rights
 *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 *  copies of the Software, and to permit persons to whom the Software is
 *  furnished to do so, subject to the following conditions:
 *
 *  The above copyright notice and this permission notice shall be included in
 *  all copies or substantial portions of the Software.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 *  THE SOFTWARE.
 */
package com.sonymobile.tools.gerrit.gerritevents.ssh;

import com.jcraft.jsch.JSch;
import com.jcraft.jsch.JSchException;
import com.jcraft.jsch.KeyPair;

import java.io.File;

/**
 * Base util for connecting, authenticating and doing stuff on an ssh client&rarr;server connection.
 * @author Robert Sandell robert.sandell@sonyericsson.com
 */
public final class SshUtil {

    /**
     * Default hidden constructor.
     */
    private SshUtil() {
    }

    /**
     * Does a series of checks in the file to see if it is a valid private key file.
     * @param keyFile the file
     * @return true if valid.
     */
    public static boolean isPrivateKeyFileValid(File keyFile) {
        return parsePrivateKeyFile(keyFile) != null;
    }

    /**
     * Parses the keyFile hiding any Exceptions that might occur.
     * @param keyFile the file.
     * @return the "parsed" file.
     */
    private static KeyPair parsePrivateKeyFile(File keyFile) {
        if (keyFile == null) {
          return null;
        }

        try {
            JSch jsch = new JSch();
            KeyPair key = KeyPair.load(jsch, keyFile.getAbsolutePath());
            return key;
        } catch (JSchException ex) {
            return null;
        }
    }

    /**
     * Checks to see if the passPhrase is valid for the private key file.
     * @param keyFilePath the private key file.
     * @param passPhrase the password for the file.
     * @return true if it is valid.
     */
    public static boolean checkPassPhrase(File keyFilePath, String passPhrase) {
        KeyPair key = parsePrivateKeyFile(keyFilePath);
        boolean isValidPhrase = passPhrase != null && !passPhrase.trim().isEmpty();
        if (key == null) {
            return false;
        } else if (key.isEncrypted() != isValidPhrase) {
            return false;
        } else if (key.isEncrypted()) {
            return key.decrypt(passPhrase);
        }
        return true;
    }
}
